Active plane modulation of Bi₂O₃ nanosheets via Zn substitution for efficient electrocatalytic CO₂ reduction to formic acid

Abstract

Formic acid is considered one of the most economically viable products for electrocatalytic CO2 reduction reaction (CO2RR). However, developing highly active and selective electrocatalysts for effective CO2 conversion remains a grand challenge. Herein, we report that structural modulation of the bismuth oxide nanosheet via Zn2+ cooperation has a profound positive effect on exposure of the active plane, thereby contributing to high electrocatalytic CO2RR performance. The obtained Zn-Bi2O3 catalyst demonstrates superior selectivity towards formate generation in a wide potential range; a high Faradaic efficiency of 95% and a desirable partial current density of around 20 mA·cm−2 are obtained at −0.9 V (vs. reversible hydrogen electrode (RHE)). As proposed by density functional theory calculations, Zn substitution is the most energetically feasible for forming and stabilizing the key OCHO* intermediate among the used metal ions. Moreover, the more negative adsorption energy of OCHO* and the relatively low energy barrier for the desorption of HCOOH* are responsible for the enhanced activity and selectivity.